Ore-treating furnace.



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PATENTBD JUNE'I, 1904.

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A. M. BEAM. ORE TREATING FURNACE. APPLICATION FILED JUNE 29.1903.

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' PATENTED JUNE 7, 1904.

A. M. BEAM. ORB TREATING FURNACE. APPLICATION nun JUNE 20,1903.

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No. 761 646- Y A. M. E M PATENTED JUNE 7, 1904.

ORE TREATING FURNACE. .APPLIOATION FILED JUNE 29,1903.

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No. 761,646. PATENTED JUNE 7, 1904.-

A. M. BEAM.

ORE TREATING FURNACE.

, APPLICATION rmzn min 29,1003. 10 MODEL.

- L /4 )ises /7/3 flfforney PATENTBD JUNE 7, 1904.

A. M. BEAM. ORB TREATING FURNACE.

APPLICATION TILED JUNE 29,1803.

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No. 761,646. PATE'NTED JUNE 7', 1904.

A. M. BEA-M. ORE TREATING FURNACE.

APPLICATION FILED JUNE 29,1903,

H0 MODEL. 8 SHEETS-SHEET9.

UNITED STATEs Patented June 7, 1904.

PATENT OFFICE.

ARON M. BEAM, OF DENVER, coLoEADo.

ORE-TREATING FURNACE.

SPECIFICATION forming part of Letters Patent No. 761,646, dated June 7, 1904.

Application filed June 29, 1903. Serial No. 163,573- (No model.)

To all whom, it may concern: I

Be it known that I, ARON M. BEAM, a citizen of the United States of America, residing in the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Ore-Treating Furnaces; andI do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference f being had to the accompanying drawings, and to the letters and figures of reference marked.

thereon, which form a part of this specification.

My invention relates to improvements in ore-treating furnaces; and the objects of my invention are, first, to provide a revolving cylindrical return-flue furnace; second, to provide an automatic rabbling rotating cylindrical furnace; third, to provide anautomatic rabbling revolving cylindrical furnace in which the ore is muflied' from contact with the products of combustion with which the furnace is heated and by which the ore is roasted; fourth, to pro-' 'vide an ore-treating furnace provided with a combustion chamber at each end; fifth, to provide an ore treating furnace having return-fines arranged to heat the furnace independent of each other or cooperatively; sixth, to provide an ore-treating furnace in which the ore feeds continuously between two heated surfaces or in which heatis applied to opposite sides of the ore as it feeds automatically and continuously through the furnace; seventh, to provide an automatically rabbling rotating cylindrical furnace in which steam can be generated and fed continuously into the furnace; eighth, to provide a furnace in which'hot air or steam is fed continuously and in which the ore is. fed continuously and is rabbled automatically in such a manner that it is picked up and dropped directly through the hot air or steam; ninth, to provide an ore-treating furnace in which the ore is fed continuously by spirally-arranged rahbling devices that lift it and drop it as aspray in the ore-chambers, and thus bring every particle of it in contact with the hottest surfaces and also in contact with the air or steam oxidizing agents that are constantly flowing into and through the furnace. I attain these objects by the mech- 1 taken along line '6 6, Fig. 5. larged sectional view through one of the inanism illustrated in the accompanying drawlngs, 1n wh1ch Figure 1 represents a side elevation of the 2 device, partly in section, intermediate parts being broken away for lack of room, while the outside casing 1s omitted. Fig. 2 represents an enlarged vertical section through the feed end of my furnace. Fig. 3 is an enlarged vertical section through the discharge end. Fig. 4 1s a longitudinal sectlon taken through the cylindrical part of my furnace, the outside casing. being omitted. Fig. 5 is an enlarged sectional View, partly in elevation; of

the discharge end section. Fig. 6-is a section Fig. 7 is an entermediate'inner sections of my furnace. Fig. 8 is an end elevation of same. Fig. 9 is an enlarged sectional view of the feed end section. Fig. 10 is a section taken through line 10 10,

T Fig. 9. Fig. 11 is an enlarged elevation, partly in section, of one of the outside sections of the furnace, the outslde casing being omitted.

Fig. 12 is asection taken along the line 12 12,

Fig. 11, looking in direction of arrow, the outside casing being shown in place. Figs. 13 and 14 are perspective views of one-half of the tread-rings used in my device. Fig. 15 is an elevation of a portion of the cylindrical part of my furnace, showing double tread-ring and roller-bearing in place, part of the outside casing being omitted. Fig. 16 is a section along line 16 16, Fig. 15. Fig. 17 is an enlarged section taken along line 17 17, Fig. 1, looking in the directionof the arrow. Fig. 18 is a section along line 18 18, Fig. 2, looking in the direction of the arrow. Fig-19 is a section taken along line 19 19, Fig. 3, looking in the direction of the arrow. Fig. 20 is a section taken along line 20 20, Fig. 3, looking in the direction of the arrow. Fig. 21 is a longitudinal central section of a section of my fur-1' nace, showing a bucket form of automatic ore rabblers and feeders. Fig. 22 is a section of Fig. 21 on line 22 22. Fig. 23 is a section taken along line 23 23, Fig. 2, showing steamboiler attachment to combustion-chamber. Fig. 24 is a section taken along line 24 24,

'Fig. 23. Fig. 25 is an end view of the smokedischarging end 5 of the flue-cylinder, and

' Fig. 26 is a section through the flue-cylinder on lines 26 26 of Fig. 3.

Similar characters of reference refer to similar parts throughout the several views.

Referring to the drawings, it will be seen that my improved ore-treating furnace consists of a plurality of concentrically-arranged cylinders 5, 6, and 7 cooperatively constructed and arranged. The length of each of these cylinders for a complete furnace is several times longer than their diameter, and in order to make the casting, assembling, handling, and shipment of them easy I make them in short sections, as shown in Figs. 3, 4, 7, 9, 11, and 21. The opposite ends of each section are provided with flanges 7 which are bolted together by bolts 8 The cylinder 5 is the inner cylinder or core of the furnace. This cylinder comprises the center flue 5 of the furnace, as at one end this cylinder enters a combustion-chamber 16, where it terminates in a ring 18, to which is bolted an outwardlyflaring collar 17, which is adapted to direct the smoke readily into the flue-cylinder.

The combustion-chamber 16 is preferably constructed of brick, and one wall 16 is built to surround loosely the ring 18 and the adjacent end of the center flue. The walls of the combustion-chamber'are bolted together with buckstays 16 and bolts and washers 19 and bolts 19 A suitable'ash-pit 16 is formed in the bottom of the combustion-chamber, and grate-bars 16 are placed above it. Suitable fire and ash-pit doors 16 and 16 are provided. At the top of the combustion-chamber a smokestack 24 is placed. While this stack could extend straight up into the atmosphere, 1 preferably curve it and connect its upper end to a second smoke-stack 28, which connects with the external flue of the furnace 6 as will be explained hereinafter. The opposite end of the flue-cylinder 5 extends into a smokestack chamber 35, where the shell of thisfluecylinder terminates in a hollow truncated cone 5. The end of this truncated cone is closed by aspider-arm flange 39. A shaft 38 is secured axially in the center of the flange, and its adjacent end extends to thecenterof the flue, where it is secured by a double ring 40 and 40, which is provided with radial arms 40, that connect the two ring portions. The inner ring fits round the shaft 38, while the outer ring 40 fits in the flue. The space between the arms forms passages for the smoke through the rings. This double ring may be secured to the shaft and flue-cylinder in any suitable manner. The smoke-chamber 35 is preferably constructed of brick bound together by bolts and buckstays, the same as the combustion-chamber 16, except that the grates and coal and ash doors are omitted and in their place a soot-door 35 is conveniently placed in it. A stack 36 connects with an outlet in the top of the chamber, and a damper 36 is placed in the stack. The opposite end while being roasted, while the annular of the shaft 38 projects through and beyond the smoke-chamber and is supported by a suitable bearing 20, which is suspended by rods 22 from a bracket attached to the top of the smoke-chamber. Two other bearings for the support of the cylinders are employed, which I will describe more fully hereinafter.

The space between the middle cylinder (3 and the central cylinder 5forms the ore-roasting chamber, through which the ore travels space 6 between the middle cylinder 6 and the outer cylinder 7 forms the outer flue, through which the products of combustion pass from the combustion-cliamber 29 to the stacks 28, as will be fully explained hereinafter. The sections of which the inner and outer cylinders are composed are all alike in size and construction with the exception of the end sections A, C, E, and F, which are built differently to allow the ore to be fed in and discharged from the furnace and to communicate with the combustion and smoke chambers. The cylinders in the various sections comprising the central flue-cylinder 5 and the middle or ore cylinder 6 are cast integral with each other, while the sections comprising the outer cylinder 7 are made separate and are detachably connected to the inner cylinders, as will A be explained farther on. The portions of the two inner cylinders comprising the feed end section A are connected by means of one or more screw partition-coils 12, which are cast integral with and located in between and winding around the outer circumference of the central cylinder 5 and the inner periphery of the cylinder 6. In the construction shown in the drawings I employ four of these screwcoils, and they form together a quadruple screw winding through the ore-space of section A up to a point a certain distance from the end of the section, at which point two or three of the partitions or screws terminate, while the remaining ones continue until the end of the section is reached. The central cylinder 5, continuing beyond the middle cylinder, terminates when in place in the combustion-chamber 16, and the helicoidal partitions 12, which also continue beyond the end of the cylinder 6, terminate in a hollow cylinder 13, integral with the screw and concentric to cylinder 5, a space G- being left between the two for the admission of air-pipes 25. Cylinder 13 is provided with a flange 13 at its outer end, and a flange 13 extends inwardly and downwardly from the outer periphery of flange 13 and terminates a certain distance from the cylinder 13, leaving an annular opening 13. The ore fed into the feedscrew may thus enter through the opening 13 into the pocket formed by flanges 13" and 13 and from there fall into the feed-screw. The cylinder 13 extends a short distance inside the ore-space between cylinders 5 and 6.

The inner sections B of the furnace,connect I is. placeda slight distance below the preceding one,-so that the ore may drop from one to the other through the apertures 10, thus being thoroughly rabbled while traveling from the feed end to the discharge end of the furnace. In lieu of these spirally-arranged introverted perforated flanges for rabbling the ore I may employ the bucket form of rabbler shown in Figs. 21 and 22. This rabbler comprises an inwardly-projecting curved shelf 71, which may be cast integral with the shell of the cylinder 6 on its inner periphery or be attached to it in any suitable manner. They preferably project from the inner periphery of the cylinder tangentially toward the peripheral surface of the flue-cylinder 5, but do not extend to it, afspace of several inches beingleft between them and radial arms 72, holding the cylinders 5 6 inv concentric position. From the upper side 71 of these projecting flanges and from their free ends backwardly-sloping partitions 71 are formed, which are preferably an integral part of the flange and inner periphery of the cylinder. These partitions are also arranged at a slight spiral angle to the transverse axis of the cylinder. (See Fig. 21.) The spiral angle or inclined pitch of these partitions causes them to act as fragmentary parts of a screw-blade surrounding the fluecylinder as they fill with ore at the bottom of the cylinder and, assuming that the section in Fig. 2 rotates in the direction ofthe arrow 71, deposit the ore farther along in the cylinder as the cylinder rotates, thus feeding the,

ore along through the cylinder. The curved projecting flanges hold the body 0f'.the ore.

The cups fill with ore, so that as they rise up as the cylinder rotates they discharge slowly and in a fine spray along the full Width of each cup. This fine spray drops through the hot air or steam onto the hot surface of the flue-cylinder to the bottom of the cylinder and is repeatedly lifted up and dropped as it is fed through the cylinder by the spirally-ar- This bucket rabbler ral partitions, and can be placed in a furnace with one or more or in alternate order with them or, if desired, can be used altogether alone instead of the others.

. The discharge-section C of the furnace is similar in construction to the intermediate sections B, with the difference that the partitions terminate ata predetermined distance from the end of the section. Cylinder 6 at this end is provided with a number of apertures 6 arranged in two circular lines along the periphery of said cylinder, the'openings alongone of the lines alternating with those along the other. I The sides of the apertures farther away from the end of the section are semicircular in shape,-which allows the ore to discharge rapidly out of the ore-space into the discharge-chamber 32, into which the end of the cylinder 6 extends. The central cylinder 5 in the discharge-section C- extends beyond the end of the middle or orc-cylinder 6, and the orifice of the latter is closed by means of a circular plate 11, which fits snugly into the end of cylinder 6 and is secured thereto by means of bolts or other suitable means. Plate 11 is provided with an outwardly-extend ing cylindrical portion 11, which fits around.

the central cylinder 5, extending beyond the ore-cylinder 6, said extension 11 forming one of the bearings of the furnace.

The several sections composing the central cylinder 5 and the ore-cylinder 6 may be secured together in any suitable manner, al

though I prefer to join them by means of a screw-thread, as shown in the drawings. To this end I reduce the outside diameters of the cylinders at one end in size and cut a thread on them, while the inside diameters at their opposite ends are counterbored and threaded to screw on the reduced threaded ends of the adjacent sections. The reduced and counterbored ends ,of-the sections are arranged so that connected sections will be even when screwed together.

threads at only one end.

The outer cylinder 7 is also divided into sections E, D, and F, section D corresponding in length to the sections B of the inner cylinders, while sections E and F are reduced in length for purposes hereinafter described. Sections E, D, and F, are furthermore provided for strengthening purposes with a number of equidistantly-located lateral ribs 7,

formed integral with the cylinder, While joinplaced equidistant in a rotative plane, each section being preferably provided with'a set adjacent to each end, with the exception of the end sections A and 0, each of which has one set. The endsof the arms 6 bear against bearing-lugs 7, which are formed on the lI1'-- ner periphery of the sections of cylinder 7 insuring the concentric arrangement of the outer and inner cylinders. The inner periphcry of cylinder 7 is furthermore provided with two lugs 7', located on each side of the bear,

in -lu 7 and which )revent theinde )endent a b 7 V l v v The feed and dischargeend sections are provided with the screwrotation of the outer cylinder, and also with stop-lugs 7 formed at the inner end of the bearing-lugs 7, lugs 7 arresting lateral movement of the outer cylinder. Lugs 7 h and 7 are located near each end of the sections; but the stop-lugs7 are only at the head end of the sections to allow the insertion of the inner cylinders from the other end. The sections of the integral inner cylinders and of the outer cylinder having been secured together and the inner cylinder inserted and put in place in the outer cylinder, the entire structure is placed horizontally upon the rollers which support the furnace during its rotating movement. The outer cylinder 7 has previously been provided with tread-rings 48 and 49, the one nearest the feed end of the furnace 49 beingcomposed of a flat ring having inwardly-extending flanges 49, While its inner periphery is provided with two or more lugs 49, which are designed to rest onthe outer edges of the flanges 7 of cylinder 7. The flanges 49 of the tread-ring 49 extend when the latter is in place on either side of flanges 7 a without coming in contact with said flanges or with the surface of the outer cylinder, thus allowing the air to circulate between the tread-ring and the cylinder. Lugs 49 'may be provided with air-apertures 49* for cooling purposes. The rollers 43, which engage the tread-ring 49, are of a width equal to that of the ring, one roller being located on each side of the furnace. Tread-ring 48, located nearest to the discharge end of the furnace, although in principle similar to the one just'described, is divided into two treads by a raised portion or circular partition 48. The inwardly-extending flanges 48 are shown to engage the surface of the outer cylinder, while the partition is provided with air-apertures 48. If so desired, this ring may be provided with bearing-lugs similar to tread 49. Tread-ring 48 rests upon two sets of rollers, the two' rollers of each set being located one on each side of the partition 48 and mounted on a common shaft. The object of partition 48 and the double rollers is to divide the expansionof the cylinders at the point where tread-ring 48 is located. The location of the dividing-ridge 48 between the stationary rollers 43 forces the cylinders to expand to both sides from this point. Both tread-rings ane made in two halves, joined together by means of bolts passing through lugs 49 and 48,

The arrangement of the roller-bearings is the same for both tread-rings, the only difference being that in the roller-bearing for tread-ring 48 double rollers are necessary to engage the divided treads, while for tread-ring 49 one heavy roller at each side is sufficient. Rollers 43 are mounted on shafts 44, supported in adjustable boxes 42, which are located on a suitable bed-plate 41. Bed-plate 41, which is secured to the foundation by means of bolts 47, provided with inverted-T-shaped slots 41 for the reception of correspondinglyshaped of the bolts 22.

bolts 46, which depend from flanges on boxes 42, passing through holes in same and held in place by means of nuts 46. By tightening or loosening nuts 46 boxes 42 will either be firmly secured to the bed-plate 41 or may be adjusted to take up wear or for the purpose of raising or lowering the cylinder. The adjustment of the boxes may be accomplished by tightening or loosening nuts 45" on a bolt 45, which connects each set of boxes.

Section F of cylinder 7, located at the feed end of the furnace, is shorter than the corresponding section of the cylinder 6, its extremity extending into a smoke-chamber 27, while cylinder 6 extends farther through the outer wall of said smoke-chamber, terminating at a point outside and in close proximity to said wall. The distance between the smokechamber 27 and the comlmstion-chanlber 10 is not only suflicient to allow for the extension of the feed-screw 12beyond the month of ore-cylinder 6, heretofore explained, and which is the point at which the ore is fed into the ore-chamber by. means of a suitable conduit 26, but it will also admit the placing of a roller-bearing between the terminal 13 of the feed-screw 12and the wall of the combustion-chamber. This roller-bearing consists of a cylindrical casing 20, which surrounds the central flue-cylinder 5 and which is provided with a series of rollers 21, upon which the cylinder bears. Casing 20 is flexibly connected to the wall of the combustion-chm):lier by means of two or more bolts 22, the lower ends of which are secured to flanges 20 of box 20, while the upper extremities extend through a bearing-block 19 of the tie-rods at the end of the furnace, said block having been made wider for this purpose. Spiral springs 23 surround the portion of rod 21 above the bearing-block and are held between the upper surface of said block and nuts 22" at the end Springs 23, supporting the weight of the end of the central cylinder 5, act as yielding medium for the axial expansion and contraction of the cylinder.

Located in between boxes 20 and the enlarged end of feed-screw 12 are two or more pipes 25, which, bent at right angles, extend into the space between the cylinder 5 and the inner cylindrical portion l3 of cylinder 13 for the introduction of air into the ore-cham- .ber, and thus supplying oxygen needed in oxidizing the oresand making what is termed an oxidizing-roast.

Smoke-chamber 27 consists of a base 27, resting on the foundation 60, and a round top portion 27 into which the end of fluec \;'linder 7 projects for a short distance, while the ore-cylinder projects through a hole in the opposite wall of top portion 27 c and beyond said wall, terminating close thereto. The top of easting 27 is provided with a smoke-outlet 27, onto which is secured a smoke-stack 28. Two dampers 27 and 28 are placed in the stack 28. The damper 28 is placed above the areshaped pipe 24, while the damper 27 e is placed below it. The function of the dampers is to direct the fumes and gases in various directions, as will be explained hereinafter. The ends of the three cylinders extending into and through smoke-hamber 27 and combustionchamber 16 are free to move laterally through end of the short end section E of the outer flue-cylinder 7 projects. A flange 7 on the outside of cylinder 7 prevents lateral movement of said cylinder in the direction of the discharge end of the furnace, and the circular hole inthe'wall of the combustion-chamber is provided with an iron lining 31, which supports the end of the flue. Surrounding the opening and extending on the inside of the combustion-chamber is a bell-shaped casting 30, secured to a flange on the lining 31, the function of the casting 30 being to direct gases, smoke, and flames into and out of fluecylinder 7. The ore-cylinder 6, extending beyond the end of flue-cylinder 7, passes through the combustion chamber 29 and into and through a discharge-chamber 32, terminating at a point flush with the outside surface of the wall of chamber 32. Thedischarge-chamber consists of a discharge-hood 32, surrounding the ore-cylinder 6 and terminating in a downwardly-extending chute 32, the whole beingv supported by means of flanged steps into a brickwork which is formed by an extension of'the walls of combustion-chamber 29. The chute terminates outside of the brick casing and may be closed by means of a slide or door 32. One or more doors 32 in the sides of the hood 32 allow the operator to take samples whenever desired. Ore-cylinder 6 is provided on its outside periphery with a flange 6, which, being located between the walls of the two chambers, checks lateral movement of cylinder 6 at this point. The top of hood 32 is provided with a fume or gas outlet 32", to which is connected a stack 34,- having a damper 32'. The ore discharges into the hood through the holes 6 in the end of the ore-cylinder, the orifice of said cylinder being closed by means of plate 11, as described above.

' The space between the outer wall of the discharge-chamber 32 and the oppositelydocated wall of the smoke-chamber 35 is suflicient to admita roller-bearing, which supports the end of the cylinder as it projects outside thedischarge-chamber. This roller-bearing consists of two rollers 33, which engage the outer periphery of the circular portion 11 of the end piece 11 and are supported in boxes in a frame is admitted through pipes 25.

33, which extends underneath the cylinder and is yieldingly supported from the bearingblock 19 in a manner identical to the one described for the bearing at the feed end.

As explained before, the extremity of the central flue-cylinder 5 is provided with a bearing-spindle 38, which extends beyond the wall of the smoke-chamber, where it is supported in a roller-bearing identical in every detail to the one already described for the feed end of the device.

My furnace being put together and mount ed as described may be rotated in any'suitable manner, although I preferably make use of the appliance illustrated in the drawings.

Around one of the sections of the outer fluecylinder 7 is placed a gear-wheel 50, which is made in two pieces and bolted together by means of bolts passing through flanges 50, the gear-wheel being secured to the cylinder by means of bolts passing through feet 50, formed integral with the gear.

gear wheel 50. Another gear wheel 53, mounted upon the same shaft, meshes into a pinion 58, which is mounted on a second shaft 57, supported in boxes 56 on bed-plate 54. This shaft is rotated by a chain. running over a sprocket-wheel 59 at the end of the shaft and extending from there to any source of power. 1

In order to retain the heat in the cylinders, I surround them with a casing 14, made, preferably, of Russian iron and secured, by means of small screw-bolts, to the ribs 7 of the outer flue-cylinder. At the points where the treadrings and gearing are located the casing is omitted.

In the roastlng of ores, and especially when roasting some characters of refractory ores,

I have found it in some cases advantageous to use steam as the oxidizing agent exclusively and instead of air and in the treatment of other characters of ores to use air alone and in others air and steam alternately. When either steam or air is used in the furnace, it

may in many cases not be located in the vicinity of a steam-boiler, and it would be too costly to erect a boiler for this particular purpose, I make use of the arrangement illustrated in Figs. 23 and 24, whereby the heat generated in one of the combustion-chambers is utilized, furnishing the required steam.

The appliance referred to consists of a steamboiler 61, made to fit into the upper portionof the combustion-chamber, its lower, surface 61 being semicircular in shape. A hollow cylinder 61, connecting the upper surface 61 with the lower surface 61, allows for the connection of pipe 24 with the combustionchamber. Boiler 61 is provided with a water.

inlet 62, a pressure-gage 63, a water-gage 64.

Secured to the "foundation 60 is a bed-plate 54, having. boxes 55, which support a short shaft 52. A .pinion 51, mounted on this shaft, meshes into IIO As the furnace and suchother appliances as may be found on ordinary steam boilers. The steam is taken from boiler 61 by two steam-pipes 65 and 66, which are connected with the steamdomes 67 and 68 on top of the boiler. Pipes 65 and 66 on leaving the domes are bentdownward and inward through the walls of the combustion-chamber, entering said chamber at points 69, a short distance below the boiler 61. The portions of the pipe inside the combustion chamber are bent downward, continuing through said chamber for a certain dis tance and leaving at right angles to its downward course at points 70 70, although, if desired, the portion in the combustion chamber may be extended into several coils to give more heating surface. The ends of pipes 65 and 66, projecting beyond the walls of the chamber, are connected by any suitable means with the pipes 25. The steam passing through the pipes inside the combustion-chamber will be superheated and introduced into the oreroasting chamber at a high temperature. When air is used, it may be admitted either hot or cold; but I preferably use hot air. A suitable blower or air-compressor, which is not shown, is connected direct to any one or to all of the pipes 25 and to a source of power, if cold air is desired; but if hot air is desired the blower should be connected to the T69 after closing the steam-pipe 66 by the valve 66 by removing the plug 69 Having thus explained the mechanism of my invention, its operation is as follows: The furnace is heated by the products of combustion passing from the combustion-chambers through the central flue-chamber 5 and the outer flue-chamber 6 The threecylinders being rotated by means of the gear-driving mechanism, the ore is fed into the ore-cylinder from a suitably-located ore-hopper through the discharge-chute 26 at a point X between the end of the ore-cylinder and the hollow ring 13, into which the feed-screw 12 terminates. The ore being thus fed into the screw is conveyed by the same through the first section of the ore-cylinder into the second section upon the perforated partitions 9, which on account of their spiral arrangement conveys the ore to the third section, and so on, until the end of the last or discharge section is reached, at which point the ore drops out of the cylinder through the apertures 6 into the discharge-chamber 32 and from there through the discharge-chute 32 into the ore-cars or other suitable receptacles. As the ore travels through the sections containing the partitions 9 it will on account of the rotary motion of the cylinders, fall continually through the apertures 10 from one partition onto the other, thus being thoroughly rabbled and getting the full benefit of the heat conveyed to the ore -cylinder from the hot products of combustion-such as gases, flames,or smoke passing through the central flue-cylinder 5 and the outer flue-cylinder 6. During the entire time required to roast an ore either cold or hot air or steam is being forced into the ore-chamber through the pipe or pipes 25, located at the feed end of the furnace. The hot air or steam on being forced through the ore-chamber has a tendency to raise or lift the ore as it drops spray-like through the apertures in the perforated partitions or from the buckets, thus surrounding every particle of ore and furnishing the oxygen necessary for oxidizing and roasting the ores. The sulfur and other deleterious elements in the ore being converted into gases flow into the hood 32 and from there through the stack into the atmosphere. This stack 34 is provided with a pipe 34, which may be utilized in case it is desired to save the sulfurous gases and convert them into sulfuric acid, the pipe being for this purpose connected with a suction blower which draws the gases out of the discharge-chamber and into a chamber where the gas will be regenerated into sulfuric acid.

When it is desired to roast an ore perfectly sweet and free, by which 1 mean to thoroughly eliminate the sulfur, arsenic, and antimony, it is only necessary to introduce a very large volume of air into the ore-chamber through the pipes 25.

In roasting certain'hinds of ores it is of advantage to have them reach a sulfate condition. Only this may be accomplished by using less air than is required for an oxidizing-roast and by increasing the rotativespeed of the cylinders enough to feed theore through it and to discharge it when in that condition.

As most ores roast better when mixed with a converting-iiux, a fluX-distributer may be placed near the feed end of the furnace, from where the flux may be conducted into the feedsection of the furnace in a manner similar to the one used for feeding the ore. This arrangement, however, is entirely separate from and in no manner part of my furnace and is not illustrated. It is naturally of advantage to get as much benefit from the heat generated in the combustion-chain]iers as is possible, and the arrangement of cylinders, combustion-chambers, and smoke-chambers as shown in the drawings is especially adaptml for this purpose. The products ofcombnstion generated in the combustion chamber 29 nearest the discharge end of the furnace are conducted through the fiue-cylimler 7, which surrounds the ore-chamber, into the smohechamber 27 and from there through stack 28 into the atmosphere, while the heat generated in the combustion-chamber l6 nearest the feed end passes through the central fluecylinder 5 and into the smoke-chamber 35 and from there through stack 36 into the atmosphere. In this case the dampers 27 and 28 and 36 in stacks 28 and 86 are opened, while the damper 24 in the arc-shaped pipe 24 is closed. If, however, we open the dainper 24 in the pipe 24 and close "damper 28 in stack 28, the gases arising from the com bustion-chamber 29'nearest the discharge end will travel through the surrounding flue-cylinder 7 into the smoke-chamber 27, from there through stack 28 and pipe 24: into the combustion-chamber 16, from wherefit returns through. the central flue-cylinder into the smoke-chamber 35, and from there through stack 36 into the atmosphere. The products of combustion generated in the combustionchamber 16 may be made to pass-through the central cylinder 5. and at the same time surround the ore-chamber by filling the surrounding flue-chamber through pipe 2 L.

Although I do not wish to limit myself to any particular sizes I have found for ordinary-sized furnaces the following proportions to be of most advantage for furnaces of from twenty-five to fifty tons capacity: The cylinder-walls I make of a uniform thickness of one and one-fourth inches, while the connecting structure maybe one and one-half inches,

' the diameter of the central fire-cylinder be ing eighteen inches. I make the diameter of the ore-treating chamber thirty-four inches and the diameter of the outside cylinder fortytwo inches, while the entire length of the furnace from feed to discharge end is twentyfour feet.

Having thus described my invention, what- I claim is 1. Inan ore-treating furnace, the combination of three concentric cylinders, combustion andsmoke chambers operatively connected with the opposite ends of two of said cylinders, means for feeding ore into, conveying through, and discharging out of the middle of said cylinders, suitable means for connecting the-cylinders, means for supporting them, and suitable means for rotating them, substantially as described.

2. In a furnace of the class described, the

. combination of substantially horizontal, concentric cylinders providing two annular and one cylindrical compartment, with suitably-v located combustion and smoke chambers, con

nected to the opposite ends of the outer and inner compartments, suitable means for feeding ore into, conveying through and discharging from the middle compartment,'suitable means for supporting said cylinder and means for rotating it, substantially as described.

. 3. In a furnace of the class described, the combination of substantially horizontal, concentric cylinders providing two annular and one cylindrical compartment, with suitably- ]ocated combustion and smoke chambers, connected to the opposite ends of the outer and inner compartments, suitable means for feeding ore into, conveying through and discharging from the middle compartment, suitable means for introducing air and steam into the middle compartment, suitable means for supporting said cylinder. and means for rotating same, substantially as described.

4:. In an ore-treating furnace,the combination with three concentric cylinders, of suitably-located combustion and smoke chambers connected to the opposite ends of the central and outer cylinders, suitable means for feeding ore into, conveying through and discharg:

ing from the middle cylinder, suitable means for conducting the products of. combustion from the outer cylinder into the central cylinder, before said products escape from the smoke-stack, suitable means for connecting the three cylinders, means for supporting them, and suitable means for rotating them,

substantially as described.

5. In an ore-treating furnace, the combination with a combustion-chamber, of a horizontal ore-cylinder, a flue-cylinder passing through said ore-cylinder and connected at one end, with the combustion-chamber, and at its other end with a smoke chamber and stack, a second flue-cylindersurrounding said ore-cylinder and connected with the combustion and smoke chambers, means for connecting the three cylinders, means for supporting them, and suitable means'for rotating them,

substantially as described.

6. In an ore-treating furnace, a horizontal ore-cylinder, a flue-cylinder, passing through the center of said ore-cylinder, its ends projecting beyond said ore-cylinder and connecting with' suitablylocated combustion and smoke chambers, one or more spiral partitions, connecting the two cylinders at the feed end of the furnace, a series of stirring devices connecting the two cylinders from the point of termination of the first-named parti-t tion to the discharge end and suitable means for supporting and rotating said cylinders, substantially as described. 7 In an ore-treating furnace, the combination with a combustion-chamber, of two fluecylinders connected 'with said combustionchamber and with a smoke chamber and stack, an ore-cylinder. placed in concentric relation to said flue-cylinders, one of them surrounding, While the other passes through said ore- =cylinder, suitably-arranged partitions con' necting said ore-cylindcr with said central flue-cylinder, including a' feed-screw at its feed end and a plurality of spirally-arranged partitions beyond said feed-screw, a plurality of ore-discharge apertures in the discharge endof said ore-cylinder, suitable means for removably securing said ore-cylinder to the surrounding flue-cylinder, means for supporting said cylinders, and sultable means for rotating same, substantially as described.

8. In an ore-treating furnace, a horizontal ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion-chamber and smoke-chamber, a second flue-cylinder concentrically located inside said ore-cylinder, its ends projecting beyond said ore-cylinder and connected with oppositelylocated combustion-chambers and smokechambers, partitions connecting the ore-cylinder with the central flue-cylinder and so arranged as to feed the ore into and convey it through the ore-cylinder, while the latter is being rotated, apertures in the discharge end of said ore-cylinder for discharging the ore, a discharge-hood surrounding said apertured end, suitable means for supporting the cylinders, and means for rotating them, substantially as described.

9. In an ore-treating furnace, the combination with a combustion-chamber, of a horizontal flue-cylinder projecting into said combustion-chamber, a bell-shaped mouthpiece surrounding the mouth or end of said flue-cylinder on the inside of said combustion-chambers, a smoke-chamber located at, and connected with the other end of said flue-cylinder, asmoke-stack and damper connected with said smoke-chamber, an ore-cylinder concentrically located inside and removably attached to said flue-cylinder, both of its ends projecting beyond the ends of said flue-cylinder and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside and rigidly connected with said ore-cylinder, its ends projecting beyond said ore-cylinder, a second combustion-chamber connected to one of said ends, a bell-shaped mouthpiece surrounding the mouth of said flue-cylinder in said combustion-chamber, a smoke-chamber located at the opposite end of, and connected with said central flue-cylinder, a smoke-stack and damper connected with said smoke-chamber, suitable means for supporting said cylinders, and suitable means for rotating them, substantially as described.

10. In an ore-treating furnace, the combination with a combustion-chamber of a fluecylinder, one end of which projects into said combustionchamber, a smoke-chamber connected to its other end, a stack connected with said smoke-chamber, an ore-cylinder concentrically located inside said flue-cylinder, and.

removably attached thereto, the ends of said ore-cylinder extending beyond said flue-cylinder and through said combustion and smoke chambers. means for feeding ore into said orecylinder at a point beyond said smoke-chamber, apertures in the end of the ore-cylinder projecting beyond the combustion-chamber, a

second flue-cylinder concentrically located inside said ore-cylind'er and connected thereto by means of partitions or spirally-arranged buckets arranged to convey the ore from the feed to the discharge end when the cylinder is being rotated, a second combustion-chamber located near the feed end and connected with the end of the central fine-cylinder projecting beyond the feed end of the ore-cylinder, a suitably-shaped pipe connecting said combustion-chamber with the stack of the smoke-chamber with which the outside fluecylinder connects, dampers located in said stack at points above and below the mouth of said pipe and in said pipe, a second smokechamber connected with the end of the central flue-cylinder, projecting beyond the discharge end of the ore-cylinder, a stack connected to said smoke-chamber, a damper located in said stack, and suitable means for rotating the ore and flue cylinders, substantially as described.

11. In an ore-treating furnace, a horizontal flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylinder, its ends projecting beyond said ore-cylinder, oppositely-located combustion and smoke chambers connected to said projecting ends, a plurality of integral partitions connecting the ore and central flue cylinders, said connected cylinders being composed of two or more sections, the cylinders in each section being provided with male threads at one end and corresponding female threads at the other end, the diameter and pitch of the corresponding threads being such that both cylinders of one section may be screwedsimultaneously onto the corresponding cylinders of the adjoining section, substantially as described.

12. In an ore-treating furnace, a horizontal flue-cylinder, a combustionchamber and a smoke chamber connected to the opposite ends of said cylinder, said flue-cylinder being composed of two or more sections, flanges at the ends of said sections, equidistant ribs formed integral with the cylindrical portion of said sections and connecting the flanges of each section, a concentrically-located ore-cylinder inside said flue-cylinder, and detachably connected therewith, its ends projecting beyond said flue-cylinder and through said smoke and combustion chambers, a second flue-cylinder concentrically located inside said ore-cylinder and connected thereto by suitably-arrangml partitions,said connected cylinders being composed of one or more sections secured together by any suitable means, a smoke and a combustion chamber respectively connected with the opposite ends of said second flue-cylinder, and suitable means for supporting and rotating said cylinders, substantially as described.

13. In an ore-treating furnace, the combination with a horizontal ore-cylinder of two flue-cylinders concentrically located inside and around said ore-cylinder, suitably-located combustion and smoke chambers connected with the ends of said flue-cylinders, suitablyarranged partitions connecting the central flue-cylinder to the ore-cylinder, means for detachably connecting the outer cylinder to the described. v

'1 In an ore-treating furnace, ahorizontal flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said I cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and

through said combustion and smoke cham-' bers, a second flue-cylinder concentrically located inside said ore-cylinder and. attached theretoby means of suitably-arranged partitions, the ends of said central flue-cylinder projecting beyond said orecylinder, oppositely-located combustion and smoke chambers receiving said projecting ends, the end projecting inside said smoke-chamber, being bell-shaped and provided'with one or more apertures, and suitable means for supporting and rotating said cylinders, substantially as described.

15. In an ore-treating furnace, a horizontal flue-cylinder, a combustion-chamber and a smoke-chamber connected to'the ends of said cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylinder and attached thereto by suitably-arranged partitions, the

ends of said central flue-cylinder projecting beyond said ore-cylinder, oppositely-located combustion and smoke chambers receiving said projecting ends, the connection between said cylinder and said combustion and smoke chambers being such as to allow the cylinders to-expand 'and contract, substantially as described.

16. In an ore-treating furnace, a horizontal fiuecylinder, a combustion-chamber and smoke-chamber connected to the ends of said cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a'second flue-cylinder concentrically located inside said ore-cylinder and attached thereto by-means of suitably-arranged partitions or lugs, the ends of said central fiuecylinder projecting beyond said ore-cylinder,

oppositely-located combustion and smoke chambers receiving said pro ecting ends,

means for feeding ore into the ore-space besaid flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers,

a second flue-cylinder concentrically located inside said ore-cylinder, its ends projecting beyond said ore-cylinder,oppositely-located combustion and smoke chambers receivlng said projecting ends, a suitable feed-screw interposed for-a certain distance between the outer circumference of the central flue-cylinder and the inner circumferenceofthe orecylinder, being integral with both said cylinders, a plurality of perforated partitions ex tending from the point of termination of said feed-screw to the discharge end of said orecylinder, being integral with both cylinders I and each partition being offset angularly with reference to the preceding one, substantially as described.

18. In an ore-treatlng furnace, a horizontal IOO flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an ore-cylinder, concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and I through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylmder,1ts ends pro ecting IIO beyond said ore-cylinder, oppositely-located combustion and smoke chambers receiving said pro ecting ends, a suitable feed-screw 1nterposed for a certain distance between the outer circumference of the central flue-cylinder and the inner circumference of the orecylinder, being integral with both said cylinders, a plurality of rabbling devices extending from the point of termination of said feedscrew to thedischarge end of said ore-cylinder, 'said rabbling devices being arranged in between the central cylinder and theore-cylindeigbeing integral with both cylinders and each partition being offset angularly with reference to the preceding one, a plurality of semicircular holes in the discharge end of said ore cylinder, a suitably shaped dischargehood receiving said discharge end, a stack connected with said discharge-hood, a damperln said stack, a pipe leading into said stack, means including a suction-blower for exhausting the sulfurous gases from said pipe and stack, means for supporting said cylinders and suitable means for rotating them, substantially as described.

19. In an ore-treating furnace, a horizontal flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylinder, its ends projecting beyond said ore-cylinder, oppositelylocated combustion and smoke chambers receiving said projecting ends, a suitable feedscrew interposed for a certain distance between the outer circumference of the central flue-cylinder and the inner circumference of the ore-cylinder, being integral with both said cylinders, said feed-screw extending beyond the end of said ore-cylinder and terminating in a cylindrical portion, concentric to the central flue-cylinder and supporting the feedscrew on its outer periphery, a flange on the outer end of said cylindrical portion, an inwardly and downwardly extending flange on the outer periphery of the first-mentioned flangefisaid second flange terminating a certain distance away from said cylindrical portion, substantially as described.

20. In an ore-treating furnace, a horizontal flue' cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a second flue-cylinder concentrically lo cated inside said ore-cylinder, its ends projecting beyond said ore-cylinder, oppositelylocated combustion and smoke chambers receiving said projecting ends, a suitable feedscrew interposed for a certain distance be tween the outer circumference of the central flue-cylinder and the inner circumference of the ore-cylinder, being integral with both said cylinders, said feed-screw extending beyond the end of said ore-cylinder and terminating in a ring concentric to and surrounding the central flue-cylinder, the portion of said ring facing the orifice of the central flue-cylinder being open, while the inside of said ring is shaped to form a pocket for the reception of the ore particles, substantially as described.

21. In an ore-treating furnace, a horizontal flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an'ore-cylinder concentrically located inside and removably connected with said flue-cylinder, the ends of said ore-cylinder projecting beyond said flue-cylinder, and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylinder, its ends projecting beyond said ore-cylinder, oppositelylocated combustion and smoke chambers receiving said projecting ends, partitions, connecting the ore-cylinder with the central linecylinder, said connected cylinders being composed of three or more connected sections, the partitions in the first or feed section being shaped to form a suitable screw-blade, while the partitions are perforated, and are spirally arranged in between the two cylinders, a series of discharge-holes in the last or discharge section, each section being provided with means for connecting it to the outer cylinder, means for supporting said cylinders and suitable means for rotating them, substantially as described.

22. In an ore-treating furnace, the combination with an ore-cylinder of a line-cylinder concentrically located inside said ore-cylinder and connected thereto by means of suitablyarranged partitions, the ends of said iiue 'linder projecting beyond the ore-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, a second flue-cylinder concentric to and surroumling said ore-cylinder and removably attached thereto, suitably located combustion and smoke chambers receiving the ends of said second cylinder, tread-rings secured to and surrounding said outer flue-cylinder, rollers mounted in adjustable boxes engaging said tread-rings, and suitable means for rotating said cylinders, substantially as described.

23. In an ore-treating furnace, the combination with an ore-cylinder of a flue-cylinder concentrically located inside said ore-cylinder and connected thereto by means of suitably-arranged partitions,the ends of said flue-cylinder projecting beyond the ore-cylinder, a combustion-chamber and a smoke-chamber connecteil to the ends of said cylinder, a second flue-cylinder concentric to and surroumling said orecylinder and removably attached thereto, suitably-located combustion and smoke chambers receiving the ends of said second cylinder, tread-rings secured to and surrounding said outer flue-cylinder, one of said rings 'beingdivided into two circular treads, separated by a circular partition, rollers mounted in pairs in adjustable boxes, engaging said treads, one roller of each pair being located on each side of said partition, and suitable means for rotating said cylinders, substantially as described.

24. In an ore-treating furnace, a Hue-cylinder, a combustion-chambcr and a smoke-chainber connected to the ends of said cylinder, an ore-cylinder concentrically located inside said flue-cylinder, being removably attached thereto, the ends of said ore-cylinder extending beyond said flue-cylinder and through said combustion and smoke chambers,an inner I luccylinder concentrically located inside said orecylinder, and connected thereto, by a suitable feed-screw and a series of perforated spirallyarranged partitions the ends of said flue-cylinder extending beyond said ore-cylinder, a combustion-chamber and a smoke-chamber receiving the ends of said inner flue-cylinder, a roller-bearing, flexibly suspended from a convenient part of said combustion chamber structure, supporting said central flue-cylinder, discharge-apertures in the opposite end of said ore-cylinder, an ore-discharge chamber receiving said apertured end, a plate secured to and closing the orifice of the orechamber at the discharge end, and having a cylindrical projection surrounding the extension of the central flue-cylinder beyond the ore-cylinder, rollers revolubly mounted in bearings on a suitable support located below 7 said cylinder, engaging said cylindrical extension of the closing-plate, rods secured to said support, an extension on the top of said discharge-chamber carrying said rods, nuts secured to the upper extremities of said rods and spiral springs surrounding said rods in between said nuts and the upper surface of said extension, substantially as described.

25. In an ore-treating furnace a flue-cylinder, a combustion-chamber and a smoke-chamber connected to the ends of said cylinder, an

ore-cylinder concentrically located inside said flue-cylinder, being removably attached thereto, the ends of said ore-cylinder extending beyond said flue-cylinder, and through'said combustion and smoke chambers, an inner fluecylinder concentrically located inside said orecylinder and connected thereto by suitable feed -screw, and a series of perforated spirally-arranged partitions, the ends of said flue-cylinder extending beyond said ore-cylinder, a combustion-chamber and a smokechamber receiving the ends of said inner flue-cylinder, a spindle secured to the end of said central flue-cylinder and projecting through the outside wall of. said smoke-chamber, a roller-bearing supporting said spindle, and an extension on the top of said smokechamber from which said bearing is flexibly suspended, substantially as described.

26. In an ore-treating furnace, the combination with three concentric cylinders, of suitably-located combustion and smoke chambers connected to the opposite ends of the central and outer cylinders, suitable means for feeding ore into, conveying through and discharging from the middle cylinder, suitable means for connecting the three cylinders, roller'bearings supporting said cylinders, a gear attached to and surrounding the outer flue-cylinder, a pinion supported in bearings meshing into said gear and suitable means for rotating the shaft of said pinion, substantially as described.

27. In an ore-treating furnace, the combinationwith a combustion-chamber of flue-cylinders connected at one end with said combustion-chamber and at the other end with a smoke chamber and stack, an ore-cylinder concentrically located relatively to said fluecylinders and connected thereto by suitable means, a boiler subjected to the heat-generated in said combustion-chamber and pipes leading from said boiler and into said ore-cylinder, substantially as described.

28. In an ore-treating furnace, an orc-cylinder, a flue-cylinder concentrically located in- 1 side said ore-cylinder, its ends projecting beyond said ore cylinder, oppositely located smoke and combustion chambers with which said projecting ends communicate, a boiler located inside said combustion-chamber, steampipes connected with said boiler and leadinginto said ore-cylinder, said pipes passing through said combustion-chamber before entering said scribed.

' 29. In an ore-treating furnace, a cylindrical flue, a combustion-chamber and a smoke-chamber connected to the ends of said flue, a bellshaped mouthpiece surrounding the orifice of said flue inside said combustion-chamber, a smoke-stack connected to said smoke-chamber, an ore-cylinder, concentrically located inside said flue and dctachably connected thereto, the ends of said ore-cylinder projecting.b c yond the ends of said flue and through said combustion and smoke chambers, a second flue-cylinder concentrically located inside said ore-cylinder, substantially as deore-cylinder and connected thereto by means of a feed-screw interposed between the central flue and the inside surface of the ore-cylinder, being integral with both, a hollow ring at the end of said feed-screw, surrounding the ex- 1 tension of the central flue and having an open ing facing the orifice of said flue, air-pipes located between said central flue and the concentric ring-shaped extension of the feed screw, one end of said pipes entering the orechamber, while its other ends are connected at a point beyond the furnace,with a suitablylocated blower, spirally arranged, rabbling devices connecting the inner flue-cylinder with the inner surface of the ore-cylinder from the point of termination of the feed-screw to the discharge end of the ore-cylinder, the inner cylinders as well as the outer cylinder being composed of connected sections, lateral ribs on the outside of said outer cylinder,a sheet-metal covering surrounding said outer cylinder and bolted to said ribs, semicircular dischargeopenings in the end of the ore-cylinder, said end extending into and through a discharge-chamber containing a hood and chute, a stack-connected to said discharge-chamber, a damper in said stack, a pipe connected at one end to said stack, while its other end is attached to a suitably-located suction-blower, a circular plate, fastened to and closing the orifice of said orecylinder and having a cylindrical projection outside said discharge-chamber, surrounding 

